Studies on Extraction of Uranium and Some Rare Earth Elements from El-Sella Area Using Chelating Resins with Amine and Amino Acid Functionality

Ahmed Abdel-Sattar Ahmed Galhoum;

Abstract


Magnetic-chitosan nanoparticles were synthesized by a simple one-step in situ co-precipitation method before being functionalized with amine moiety (diethylenetriamine) and different amino acids moieties (i.e., alanine, serine and cysteine) using epichlorohydrin as the linking agent. The structural and functional characteristics were investigated by elemental analysis, FT-IR, XRD, TEM and VSM analysis. In a second step, the sorption properties of these materials were tested for recovery of U(VI) and REE(III) from aqueous solution: pH effect, uptake kinetics and sorption isotherms were investigated.
The sorbents particles are super-paramagnetic and in nanometric size. Kinetic profiles are successfully modelled with the pseudo-second order rate equation. The Langmuir and the Dubinin–Radushkevich (D–R) equations fit well sorption isotherms.
The maximum adsorption capacities at pH 3.61-5.00 ± 0.01 (optimum pH, and at T: 25 ± 1 °C) are close to 85.33, 97.35, 116.29 and 177.93 mg U g−1 for alanine, cysteine, serine and amine type, respectively. The adsorption is chemical in nature by coordination (the activation energy EDR > 8 kJ/mol). Uranyl ions (UO22+) in aqueous solution appear to be adsorbed by combined chelation and anion-exchange mechanisms. Temperature shows a negative effect on UO22+ ions adsorption. In addition the values of thermodynamic parameters (∆Go and ∆Ho) show that the process is spontaneous and exothermic. The positive value of ∆So means that the randomness of the system increased with sorption. Finally, the adsorbent can be efficiently regenerated and recycled for at least 5 cycles using acidified urea as the eluent.
The adsorption affinity of all adsorbents toward the three REEs(III) ions (Nd, Dy and Yb) follows the sequence: Yb(III)>Dy(III)>Nd(III); at pH 5 (optimum pH, time 4 hrs and at T: 27 ± 1 °C). The sorption capacities of the different materials for Dy(III) ions are in the following order: amine (50.3 mg g-1) > cysteine (15.8 mg g-1) > alanine (12.8 mg g-1) > serine (7.4 mg g-1). The values of ΔG° and ΔH° indicate the spontaneous and endothermic nature of the mechanism while the positive values of ΔSo show that during the sorption process the randomness increases. Cationic species REEs (III) in aqueous solution could be adsorbed by the combination of chelating and anion-exchange mechanisms with a physicochemical process. The adsorbents can be regenerated with high efficiency using acidified thiourea as the eluent.
Finally, application of the bench scale results to the extraction of uranium and some rare earths from El-Sella ore sample. The recovery of uranium as sodium di-uranate (Na2U2O7) was about 84.81 % U. The recovery of some rare earths as oxide was about 89% RE2O3; the major impurities were Na, Al and traces of Ca and Mn.


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Keywords: Magnetic-chitosan nanocomposites; Amine; Amino acids; Uranium(VI); Dy(III); Kinetics; Isotherms; El-Sella ore.


Other data

Title Studies on Extraction of Uranium and Some Rare Earth Elements from El-Sella Area Using Chelating Resins with Amine and Amino Acid Functionality
Other Titles دراسات على أستخلاص اليورانيوم وبعض العناصر الأرضيه النادره من منطقة سيلا بأٍستخدام راتنجات مخلبية ذات أمينات وأحماض أمينية كمجموعات وظيفية
Authors Ahmed Abdel-Sattar Ahmed Galhoum
Issue Date 2015

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